Iceclimber were brawl iceclimber that could wavedash/l-cancel and they never show oilmar.
I see where you're getting at, don't get me wrong, but I'm speaking of of speculation and they all were shown and talked about at some point. Olimar was shown
really early in development and the only thing changed then was it took 4 seconds to pluck every pikmin. After that, he was only talked about. There was something a while back about rumors of the pikmin getting stronger the further they bloomed, but that was a long time ago. And as for Ice Climbers, or "GlitchClimbers", have resulted in the engine itself changing and not the characters. They were making fun of their glitchy movements not long before Demo 2's release and my guess is that they have yet to find the solution to the problem. I would say don't get your hopes up seeing them any time soon.
As for Diddy, little official talk has been said after breifly showing him. All people noticed were his then one banana peel limit and horrible looking recovery, the ladder in which maybe the result of the stage walls having yet to be modified. I can't tell you much about his progress.